PAT甲级——A1067 Sort with Swap(0, i)

Given any permutation of the numbers {0, 1, 2,..., N−1}, it is easy to sort them in increasing order. But what if Swap(0, *) is the ONLY operation that is allowed to use? For example, to sort {4, 0, 2, 1, 3} we may apply the swap operations in the following way:

Swap(0, 1) => {4, 1, 2, 0, 3}
Swap(0, 3) => {4, 1, 2, 3, 0}
Swap(0, 4) => {0, 1, 2, 3, 4}

Now you are asked to find the minimum number of swaps need to sort the given permutation of the first Nnonnegative integers.

Input Specification:

Each input file contains one test case, which gives a positive N (≤) followed by a permutation sequence of {0, 1, ..., N−1}. All the numbers in a line are separated by a space.

Output Specification:

For each case, simply print in a line the minimum number of swaps need to sort the given permutation.

Sample Input:

10
3 5 7 2 6 4 9 0 8 1

Sample Output:

9

 #include <iostream>
 using namespace std;
 int m = , N, nums[], flag = , index = ;
 int main()
 {
     cin >> N;
     for (int i = ; i < N; ++i)
         cin >> nums[i];

     while (index<N)
     {
         while (nums[] != )
         {
             swap(nums[], nums[nums[]]);
             ++m;
         }
         for (; index < N; ++index)//使用index，不用每次从0开始遍历
         {
             if (index != nums[index])
             {
                 swap(nums[], nums[index]);
                 ++m;
                 break;
             }
         }
     }
     cout << m << endl;
     return ;
 }